The compound N-(3-(5-(4-chlorophenyl)-1H-pyrrolo[2,3-b]pyridine-3-carbonyl)-2,4-difluorophenyl)propane-1-sulfonamide or propane-1-sulfonic acid {3-[5-(4-chloro-phenyl)-1H-pyrrolo[2,3-b]pyridine-3-carbonyl]-2,4-difluoro-phenyl}-amide (Vemurafenib) is a BRAF enzyme inhibitor effective for the treatment of diseases such as metastatic melanoma, thyroid cancers and colorectal cancers. It has the chemical formula (I) presented below.

The synthesis of the compound of formula (I) has previously been described in WO 2007/002433, WO 2011/015522, and WO 2012/010538. The process described in WO 2011/015522 however suffers from the protection-deprotection strategy in the last steps which significantly decreases the overall yield, while the raw material, 1-ethoxyethene-2-boronic acid pinacol ester, used in WO 2012/010538 is an expensive reagent which is difficult to prepare.
Thus, it is desirable to provide an improved method for producing vemurafenib in high yield and purity. The utilization of new raw materials gives a process which is more cost efficient and suitable for use on large scale than the processes known in the prior art.